Propellent powder



June 26, 1945. H. B. ALEXANDER PROPELLENT POWDER Filed July 20, 1943 HARVEY B. ALEXANDER ATTORNEY Patented June 26, 1945 2,379,056 v f PaorELLENr POWDER Harvey B Alexander, KenviL'N. J., assigner to Hercules Powder Company, Wilmington, Del., a

corporation of Delaware Application July 20, 1943, Serial No: 495,535

(Cl. l02-38) 6 Claims.

This invention relates to a progressive-burning propellent powder, and more particularly to an unmodified double base smokeless powder of progressive-burning character` lwhich is especially suitable for use in high velocity .22 caliber rimiire ammunition.

It is `well known that .22 caliber rim-fire cartridges are loaded with progressive-burning smokeless powder which has characteristics that give certain definite desirable pressure and velocity relations. To obtain these relations when double base powders are used, it is customary to coat the grains of smokeless powder with` a deterrent material, which coating so modifies the grains that their initial burning rate is retarded and the powder burns so that successively exposed surfaces contain less and less of the deterrent material and thus the combustion 4of the grains is caused to proceed with increasing speed. Although modied double base powder grains give excellent ballistics, they are more costly to prepare since their preparation involves extra operations and added ingredients.

Coated powder grains are also subject to several shortcomings, one of which is that the deterrent layer under certain conditions of hot storage may tend to diffuse through the inner portions of the grains. Thus the layer is lost from the surface of the grain giving rise to high initial pressures when the powder is fired. A coated powder requires increased charge weight for the coating agents do notadd to the potential of the powder.

An Iunmodified grain therefore is more eiiicient 'than a corresponding modified powder.

Now,in accordance with this invention, it has been found that desirable ballistics can be obtained from an unmodified double base powder when it isloaded into .22 caliber rim-fire cartridges if the composition includes certain definite percentages of nitrogiranidine, nitroglycerin, and nitrocellulose.

' In more detail, it has been found that an admixture containing between about 10 and about nitroglycerimbetwe'en about 10 and about nitroguanidine, between about 50 and about 80% nitrocellulose, and the normal amount usu- /ally .50 to 1.25% of a stabilizer, when admixed with normal smokeless powder solvents such as ethyl alcohol, ethyl ether and acetone to form a colloided mass, pressed into strands and cut into grains, produces powder grains which when glazed f and sieved gave desirable ballistics in .22 caliber rim-fire cartridges. 'The double base powder grains prepared as above are not surface modified, as the` composition when maintained within the percentages indicated gives ballistics that are'- comparable to standard double base coated powders. 'Ihe ballistics obtained compare favorably in charge weight, breech pressure, and instrument velocity. i

The nature and purpose of this invention have been indicated in a general way. There now follows a more detailed description of a preferred embodiment thereof with reference to the accom-v panying drawing, in which the single figure represents a .22-caliber rim-fire cartridge.

In the single figure the cartridge includes a metallic casing I, usually of brass or copper, which has a lead or similar bullet 2 inserted and clamped into its open end. The breech end of the cartridge contains a priming composition 3, which usually consists of a detonatlng material and an abrasive material. 'Ihis priming composition is positioned within the annular space formed when the cartridge is upset. In the cartridge casing I there is a charge of smokeless powder of the t'ype which has been found useful in the-invention. Described hereinafter, the powder consistsl of grains 4 of an unmodified double-base powder.

To indicate the compositions which when in accordance with this invention are admixed, colloided, pressed, and cut into grains give smokeless powders that are suitable for use in an uncoated condition in .22 caliber rim-fire cartridges, the following examples are given:

EXAMPLE 1 An admixture of 15% nitroglycerin, 10% nitroguanidine, 74.25% nitrocellulose, and .75% diethyldiphenylurea was mixed with an alcoholacetone solvent mixture in a W and P mixer until colloided to give a substantially uniform powder mass, pressed'into strands, and cut into grains. The grains thereafter were dried, glazed, and sieved. The grains were not modified by any type surface coating, but when tested in .22 caliber is compared .t0 commercial powders coated with standard modifying agents,

Tnx.: 1

Uncoated nitroauanidine powder: compared to coated nitroalucerin powders in .22 cal. rim fire cartridves Percent Percent Mean Mean pres- Grammi Example nitronitroggt m velocity sure, dlf'mx Coating glycerin n lsec. iba/aq. in. inches 2 15 15 2. 15 1, m5 22, 1w .m8 X 1/175 NOO l.

15 30 2.02 1, wi 22, m .041 X 1M NODO 3 15 .12 2.16 1,307 217m .m8 X 1/175 N182 l m 2. 1, w 21, .s X 1,/175 NODO. 4 15 12 2. 18 1, 302 22, 1w .S X 1/175 NUM 2 15 10 2. 1B 1, 297 21, w .03B )C1/150 011B. 5 15 l2 2. 16 1, 971 21,@ .038 X 1/175 N020 2 m w 1. W 1, 279 22, m .041 X 1/175 NODQ. 6 15 12 ZN 1,306 22m .038 X 1/175 NOM 2.

2. 10 1, m 22, m .041 X 1/175 NODO. 7 15 .12 2.x 1,2% 21,7 .8X1/175 NO02 10 m 2. 25 1, 297 m, m .041 X 1,1m N038. 8 15 .12 2.24 1,2m 22,@ .038)(1/175 NO02 10 m 2. 27 1, m2 22, m .041 X m75 N119. 9 15 12 2. 25 1, 295 21, m .038 X 1/175 Note 2.

m 50 2. 21 l l, 3% 21, m X 1./150 NODE.

Bunch-Remington 40 gr. lead. Note 1.--Powder coated with diethyl phthalate-2.1%. Nou 1.-(Mding.- thy ethyl centralita-0.75%; nitrocellulose (13.21% N)remainder.

It is seen from the data in Table 1 that the present invention produces powders which are the full equivalent in ballistics of desirable commercial powders without .the need of coating the individual grains. Normal nitroglycerin powders containing no nitroguanidine will not give the desirable ballistics unless coated. This difference in coated and uncoated nitroglycerin powders is shown below.

TABLE 2 l o-benzoyl benzoate 0.9%, butyl phthalyl butyl'glycollate 0.9%, substantially petrodinees indicated; nitroglycerin-as indicated; KNO,-as indicated;

use in .22 caliber rim-nre ammunition contains about"% nitroguanidine. The nitroguanidine is preferably used in finely divided condition which is the ordinary form in which the compound is obtained.

The nitroglycerin which is used in the powder of this invention is normal smokeless powder u nitroglycerin. This nitroglycerin may be used in a range between about 10 and about 20% and the Comparison of coated and uncoated mtroalycerin powders in .22 cal. rim fire cartridges Bailar-Remington 40 gr. lead. Non 1.-Coating ethyl Digg. mstantially petroleum insoluble pine wood resin (Vinsol) Granuletion Percent Mean Mean Percent Charge diameter X nitrovelocity, pressure Coating giyrm KNO mms msec. iba/sq. nl. eilltesm l5 12 2. 24 1,304 21, 700 .038Xl/175 Note l 15 l2 l. 73 l, 221 2l, 700 038)(1/175 None obenzoyl benzoate 0.9%, butyl phthall butyl glycollate .4.7 tut.-Iformida.-Nitroglycerin-as indicated; KNOi-as indicated; ethyl centralita-0.75%; nitrocellulose (13.21% N)-remaiuder.

The nitroguanidine which is used in the powders of this invention may be prepared by sulfurie acid digestion of guanidine nitrate and is a well-known composition in the explosive art. The material is white, crystalline in nature, and is easily purified. The stability thereof is equivalent to the other ingredients used in smokeless powder. In .the preparation of the smokeless powder containing nitroguanidine, some care must be taken to prevent loss of nitroguanidine due to its solubility in cold water. In some instances, water is used in the manufacture of powder, but it is desirable when manufacturing nitroguanidine powder to minimize the exposure of the powder to water or to use water which is saturated with nitroguanidine, thus reducing leaching of the nitroguanidine from the powder grains.

In producing the powders in accordance with this invention, the nitroguanidine will be present between about 10 and about 30% by weight otthe composition but the preferable powder for preferable powder of this invention contains 15% by weight nitroglycerin. Nitroglycerin contents greater than about 20% are undesirable because they render the powder grains sticky, preventing easy loading and further cause desensitization of primers during storage. Y

The nitrocellulose which is used in the powder of this invention is one of the smokeless type, i. e., containing at least about 13% nitrogen and preferably around 13.2% nitrogen. The nitrocellulose content of the powder may be varied over a wide range. In the powder of the present invention, it may be varied from about 50 .to about 80%, but is preferably present between about 65 to about In all smokeless powders, a stabilizer is used, and in the powder of this invention, a standard stabilizer is also used. In general, stabilizers are added to the powder composition after it is put in the mixer and the added stabilizer usually amounts to about 1% of the composition in the mixer, i. e., approximatley 1 pound of :stabilizer is added for every 99 pounds of powder composition. The powder of the present invention uses approximately the same amount of stabilizer as normal smokeless powder. Further, the stabilizer used can be any of the accepted stabilizers, for example, diphenylamine, diethyldiphenylurea, or the like.

In the mixing procedure, solvents must be used and the solvents used for preparation of the present powder may be any of the standard solvents or mixtures thereof; Alcohol, ether, and acetone are suitable. The present powder, however, is most easily colloided when an acetone/alcohol mixture is used as the solvent.

In some instances, oxidizing agents are added to smokeless powder. These oxidizing agents are materials such as barium or potassium nitrate. If desired, small amounts of such oxidizing agents, i. e., up to about 0.5% may be added to the powder of the present invention. However, the preferable compositions of this invention do not contain such oxidizvers.

The granulation of the powders of the present invention runs parallel to the granulation procedures and ranges used to produce the various commercial .22 caliber rim-fire powder. In general, the grains are about .03 to about .04 inch in diameter and between about 1/75 to 1/zoo of an inch 'in thickness. The granulation, of course, affects the charge weights and the burning speed of the powder but such regulations of the granulation are well within the skill of the art.

The unmodified double base powder of this invention finds its main use in high velocity .22 caliber rim-fire ammunition and in such ammunition it is the full equivalent of coated powders now on the market. The powder of this invention being uncoated has many inherent advantages over coated powders. The uncoated powder is more uniform since there is no question as to even distribution of coating material, is easier to prepare because the coating operation is unnecessary and it is'more economical since the manufacturing cycle is reduced by the time necessary to eiect coating and the cost thereof. An additional advantage of the present uncoated powder over modified double base powders is that the former are not subject to ballistic changes in hot storage arising from diffusion of a surface coating into the interior portions of the grains.

What I claim and desire to protect by Letters Patent is:

1. Unmodied progressive-burning smokeless powder grains suitable for use in .22 caliber rimre ammunition comprising a uniform colloid containing between about 10 and about 20% nitroglycerin, between about 10 and about 30% nitroguanidine, between about and about 80% nitrocellulose, and a stabilizer.

2. Unmodied progressive-burning smokeless powder grains suitable for use in .22 caliber rimre ammunition comprising a uniform colloided admixture containing about 15% nitroglycerine, between about 10 and about 30% Anitroguanidine, and between about and about '75% nitrocellulose, and between about .5 and about 1.25% of a stabilizer.

3. Unmodied progressive-burning smokeless powder grains suitable for use in .22 caliber rimre ammunition comprising a uniform colloided admixture containing about 15% nitroglycerin, about 20%' nitroguanidine, about 64% nitrocellulose, and about 1% added stabilizer.

4. A .22 caliber rim-fire cartridge comprising a casing, a priming charge at the rim thereof, a progressive-burning smokeless powder charge, and a metallic bullet, said smokeless powder charge comprising unmodified grains composed of between about 10 and about 20% nitroglycerin, between about 10 and about 30% nitroguanidine, between about 50 and about 80% nitrocellulose, and a stabilizer.

5. A .22 caliber rim-fire cartridge comprising a casing, a priming charge at the rim thereof, a progressive-burning smokeless powder charge, and a metallic bullet, said smokeless powder charge comprising unmodified grains composed of about 15% nitroglycerin, between about 10 and 30% nitroguanidine, and between about 65 an nitrocellulose, and between about .5 and about 1.25% of a stabilizer.

6. A .22 caliber rim-fire cartridge comprising a casing, a priming charge at the rim thereof, a progressive-burning smokeless powder charge, and a metalic bullet, said smokeless powder charge comprising unmodified grains composed of about 15% nitroglycerin, about 20% nitroguanidine, about 64% nitrocellulose, and abou 1% added stabilizer. f

HARVEY B. ALEXANDER. 

